The statements in this section merely provide background information related to the present disclosure and do not constitute prior art.
Moving Picture Experts Group (MPEG) and Video Coding Experts Group (VCEG) have developed an improved and excellent video compression technology over existing MPEG-4 Part 2 and H.263 standards. The new standard is named H.264/AVC (Advanced Video Coding) and was released simultaneously as MPEG-4 Part 10 AVC and ITU-T Recommendation H.264. Such H.264/AVC (hereinafter referred to as ‘H.264’) uses a spatial predictive coding method, which is different from known video coding-related international standards such as MPEG-1, MPEG-2, MPEG-4 Part2 Visual and the like.
The inventor(s) has noted that known video coding methods use “intra prediction” for coefficients transformed in discrete cosine transform domain (or DCT transform domain) to seek higher encoding efficiency resulting in degradation of the subjective video quality at low band transmission bit rates. However, the inventor(s) has also noted that H.264 adopts a method of encoding based on a spatial intra prediction in a spatial domain rather than in a transform domain.
Encoders using an encoding method based on the known spatial intra predictions predict pixels of a current block to encode from pixels in the previous blocks that underwent encoding and then decoding into the reconstruction, encode just the differences of the predicted block pixel values from pixels values of the current block and, transmit the encoded difference information to a decoder. Then, the encoder is supposed to transmit parameters needed for prediction of the block pixels, i.e. information on the intra-prediction mode to the decoder, or both the encoder and decoder may be made to use just a predefined intra-prediction mode, so that the decoder makes the same predictions as the encoder.
Therefore, the inventor(s) has experienced that at every event of block encoding, the intra-prediction mode of the corresponding block is encoded, when it requires to encode and transmit the intra-prediction mode information per block, the amount of bits generated from the encoding operation increases, which in turn increases the amount of data in encoding of videos and leads to the degradation of the overall video compression performance.